The present invention relates to small magnetic tape cassettes, and more particularly to a miniature video magnetic tape cassette in which a guard panel covers an opening formed in the front part of the cassette body through which the magnetic tape can be extracted for playing and recording.
Magnetic tapes and magnetic recording and reproducing devices are continually being improved in performance. There has been a strong demand for provision of a portable video system which is more mobile than a conventional stationary video system and can be used outdoors. In order to meet this requirement, it is essential to miniaturize not only the video equipment but also the magnetic tape cassettes used therewith.
When a video magnetic tape cassette is loaded into a magnetic recording and reproducing device (VTR-video tape recorder), a mechanism in the device operates so that the magnetic tape is pulled out of the cassette through an opening formed in the front part of the cassette for recording or reproducing signals.
When the cassette is not in use, in order to protect the magnetic tape from damage, the opening is closed by a guard panel which is pivotally supported by the side walls of the cassette and urged toward the closed position at all times.
FIG. 1 is a perspective view showing the essential components of a conventional cassette of the type having a tape withdrawal opening formed in the front part of the cassette covered by a guard panel which is elastically urged to close the opening at all times. As shown in FIG. 1, a torsion spring 1 is disposed around a shaft 4 which protrudes from the inner surface of a side wall 3 of the guard panel 2. One end of the spring is abutted against the inner surface 5 of the front portion of the upper wall of the cassette, while the other end is locked to a protrusion 6 which extends from the cylindrical surface of the shaft 4. The spring 1 urges the guard panel 2 toward the closed position.
With the protrusion 6 extending from the cylindrical surface of the shaft 4 on the side wall 3 of the guard panel 2 as described above, since the torsion spring 1 is relatively long, the length of the shaft 4 protruding inside the cassette is relatively large and it is necessary to provide a large space to accommodate the shaft 4. In assembling the cassette, with one end of the spring 1 locked to the protrusion 6 and with the other end temporarily retained on the inner surface 7 of the upper wall of the guard panel 2, the front part 5 of the upper wall of the cassette is engaged with the upper wall of the guard panel 2 in such a manner that the front part 5 of the upper wall of the cassette is set below the inner surface 7 of the upper wall of the guard panel 2. In this operation, the other en of the spring 1 is moved from the inner surface 7 of the upper wall of the guard panel 2 to the inner surface of the front part 5 of the upper wall of the cassette. Due to the fact that the other end of the spring is temporarily retained on the upper wall of the guard panel, and hence that the assembly of the cassette cannot be achieved without temporarily retaining the spring on the upper wall of the guard panel, the conventional magnetic tape cassette cannot always be easily miniaturized. Moreover, as the other end of the spring is temporarily retained on the upper wall of the guard panel as described above, cassette assembly is difficult to satisfactorily carry out when the various components thereof are miniaturized.
An object of this invention is thus to provide a miniaturized magnetic cassette tape in which the above-described difficulties accompanying a conventional magnetic tape cassette have been eliminated and which can be readily assembled.